DE102018208069A1 - Axial piston machine with recess in the area of the signal pressure channel - Google Patents

Abstract

The invention relates to an axial piston machine with a housing (11) which is provided with a cylinder bore (50), wherein in the cylinder bore (50) an actuating piston is received linearly movable, wherein by means of the actuating piston, a displacement volume of the axial piston machine is adjustable, wherein the cylinder bore ( 50) is provided at an outwardly open end with an internal thread (51), in which a closure screw is screwed, so that there is a closed cylinder space between the control piston and the screw plug, wherein in the housing (11) has a fluid channel (43) is arranged, which is fluidly connected to the cylinder chamber. According to the invention, a recess (60) which is deeper than a thread depth (52) of the internal thread (51) is arranged in the area of the internal thread (51), so that a bottom area (62) of the recess (60) is free from threads (54) wherein the fluid channel (43) opens out in said bottom region (62).

Description

The invention relates to an axial piston machine according to the preamble of claim 1.

From the catalog, which was available on April 10, 2018 under the Internet address http://www.boschrexroth.com/various/utilities/mediadirectory/download/ index.jsp? Object_nr = RD91706-01-B, an axial piston machine is known. This is operated as a motor, the present invention is also applicable to pumps. This axial piston machine is formed in a swash plate design, wherein the present invention is also suitable for an axial piston machine in bent-axis design.

The axial piston machine has an actuating piston, by means of which the displacement volume of the axial piston machine is adjustable. In the present case, the pivoting cradle is adjusted with the adjusting piston. In an axial piston in Schrägachsenbauweise could also be moved with the control piston and the control lens.

An advantage of the present invention is that in a cylinder bore with predetermined dimensions, a particularly large travel of the actuating piston can be achieved. In this case, the strength of the axial piston machine, in particular that of the housing, not adversely changed. The axial piston machine can be operated with unchanged operating pressure.

According to the independent claim it is proposed that in the region of the internal thread a recess is arranged, which is deeper than a thread depth of the internal thread, so that a bottom portion of the recess is free of threads, wherein the fluid channel terminates in said bottom portion. The fluid channel preferably discharges completely in the bottom region, wherein it is most preferably arranged at a distance from the edge of the bottom region.

The fluid channel is preferably connected to a control valve, by means of which, for example, the delivery pressure of the axial piston machine can be adjusted by adjusting the displacement volume to a predetermined value. The fluid channel is accordingly also referred to as a signal pressure channel.

In the dependent claims advantageous refinements and improvements of the invention are given.

It can be provided that the recess, when viewed in a sectional plane which is aligned perpendicular to the central axis of the cylinder bore and which extends through the fluid channel, is circular, so that its width in the region of the thread crests of the internal thread is at least twice as large the diameter of the fluid channel. Such a recess is particularly simple and inexpensive to produce with a side milling cutter or a ball cutter. The material stress in the region of the recess is the smaller, the larger the outer diameter of said cutter. It is understood that this outer diameter is preferably chosen just large enough that the material strength is sufficient.

It can be provided that the recess, when viewed in a sectional plane which contains the central axis of the cylinder bore and which extends through the fluid channel, is trapezoidal, wherein the fluid channel opens completely in the corresponding planar bottom region. This results in a clearly defined floor area. The bottom region is preferably arranged parallel to the central axis of the cylinder bore.

It can be provided that the recess, when viewed in a sectional plane which contains the central axis of the cylinder bore and which extends through the fluid channel, is circular. This results in particularly low material stresses in the region of the fluid channel. The corresponding recess can be produced for example by means of a ball milling cutter.

It can be provided that the recess is rotationally symmetrical with respect to an axis of symmetry, which runs parallel to the central axis of the cylinder bore and which is arranged in the interior of the cylinder bore. Such a recess can be easily produced with a disc or a ball cutter.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

• 1 einen Längsschnitt einer erfindungsgemäßen Axialkolbenmaschine;
• 2 einen Teillängsschnitt des Gehäuses der Axialkolbenmaschine nach 1;
• 3 einen grobschematischen Teilschnitt der Axialkolbenmaschine nach 1 im Bereich der Ausnehmung;
• 4 einen weiteren grobschematischen Teilschnitt der Axialkolbenmaschine nach 1 im Bereich der Ausnehmung;
• 5 einen der 4 entsprechenden Teilschnitt einer weiteren Ausführungsform der Ausnehmung.

The invention will be explained in more detail below with reference to the accompanying drawings. It shows:

• 1 a longitudinal section of an axial piston according to the invention;
• 2 a partial longitudinal section of the housing of the axial piston after 1 ;
• 3 a rough schematic partial section of the axial piston according to 1 in the region of the recess;
• 4 a further rough-schematic partial section of the axial piston according to 1 in the region of the recess;
• 5 one of the 4 corresponding partial section of another embodiment of the recess.

1 shows a longitudinal section of an axial piston according to the invention 10 , The axial piston machine 10 includes a housing 11 , which has a housing base body 12 and a connection plate 13 includes. The housing body 12 is pot-shaped, with its opening from the connection plate 13 is closed. In the connection plate 13 are two in 1 not visible fluid connections provided, namely a suction port and a pressure port.

In the case 11 is a drive shaft 20 by means of two pivot bearings 22 with respect to a rotation axis 26 rotatably mounted. The pivot bearings 22 are presently designed as tapered roller bearings. The drive shaft 20 protrudes with a drive pin 21 out of the case 11 out so that it can be brought into rotary drive connection, for example, with an electric motor. Between the two pivot bearings 22 around the drive shaft 20 around is a cylinder drum 23 arranged, which in rotary drive connection with the drive shaft 20 stands. The cylinder drum 23 is in the depressurized state via a spring 24 against a control plate 34 pressed, which in turn on the connection plate 13 is supported. During operation, a hydraulic contact pressure also acts. The control plate 34 is provided with at least two control apertures, which are each fluidly connected to an associated fluid port. The control plate 34 is preferably made of brass. It is non-rotatable with the connection plate 13 connected, the cylinder drum 23 relative to the control plate 34 is rotatable.

In the cylinder drum 23 are several power pistons 30 added. The working pistons 30 are uniformly distributed around the axis of rotation 26 arranged around, wherein they are aligned substantially parallel to this. The working pistons 30 limit together with the cylinder drum 23 each a work space 27 with variable volume. By turning the cylinder drum 23 are the workrooms 27 alternately with one of the control openings in the control panel 34 can be brought into fluid exchange connection.

The working pistons 30 stick out of the cylinder drum with one end 23 out, being there with a tilting sliding shoe 31 are provided. The sliding shoe 31 slides on a flat sliding surface on a pivoting cradle 32 , where he from the pressure on the work spaces against the pivoting cradle 32 is pressed. So that the sliding shoes 31 also in unpressurized condition of the position of the pivoting cradle 32 follow, is a retreat plate 33 provided, which on a spherical surface of a pressure ring 25 is supported. The pressure ring 25 is preferably fixed to the drive shaft 20 connected.

The pivoting cradle 32 is with respect to a pivot axis 35 pivotable in the housing body 12 stored, for example by means of two plain bearings. The pivot axis 35 runs perpendicular to the axis of rotation 26 where it either cuts or is located at a small distance to this.

The housing 11 is with a cylinder bore 50 provided in which a control piston 40 is received linearly movable. The adjusting piston 40 is integral with a piston rod 45 provided, which end to the pivoting cradle 32 is supported. The comparatively thin piston rod 45 allows a low tilting movement of the actuating piston 40 so that this at an adjustment of the pivoting cradle 32 not stuck.

The cylinder bore 50 is outward with a screw plug 41 closed, so that between the screw plug 41 and the actuator piston 40 a fluid-tight cylinder space 42 results. If it passes through the fluid channel (# 43 in 2 ) is pressurized, the adjusting piston moves 40 to the pivoting cradle 32 out, so the swing cradle 32 is adjusted. As a result, the displacement volume of the axial piston machine changes 10 ,

One against the force of the actuator piston 40 Directed restoring force can by means of a (not shown) return spring on the pivoting cradle 32 and / or by the eccentric arrangement of the pivot axis 35 be achieved.

2 shows a partial longitudinal section of the housing 11 the axial piston machine 10 after 1 , The cutting plane is the same as that of the 1 , The cylinder bore can be seen 50 which are in a circular cylindrical area 53 circular cylindrical with respect to a central axis 56 is trained. In this smooth area 53 is the actuator piston 40 sealingly. To the circular cylindrical area 53 closes an internal thread 51 immediately. There is the screw plug (No. 41 in 1 ), which screwed the cylinder bore 50 closes to the outside. Usually, the fluid channel opens 43 in the circular cylindrical area 53 because this place is optimal for strength reasons.

In the context of the present invention is intended in a cylinder bore 50 with predetermined dimensions, a particularly large travel of the actuating piston 40 be achieved. That's why the fluid channel 43 in the area of the internal thread 51 laid. It has been shown that there the strength of the material of the housing 11 is no longer sufficient to permanently endure the material stresses occurring during operation. To remedy this problem, the recess according to the invention has become 60 introduced, whose form with respect to 3 to 5 is explained in more detail.

3 shows a partial section of the axial piston machine 10 after 1 in the region of the recess 60 , The cutting plane is aligned perpendicular to the central axis of the cylinder bore, passing through the fluid channel 43 runs. The fluid channel 43 typically has a circular cross-sectional shape with the diameter 44 , The recess according to the invention can be produced, for example, by means of a disk milling cutter whose axis of rotation runs parallel to the central axis of the cylinder bore, so that it can be easily inserted into it. The recess 60 is therefore rotationally symmetrical with respect to an axis of symmetry 72 , which coincides with said axis of rotation.

The outer diameter of the side milling cutter or the milling diameter 71 is significantly larger than the diameter 44 of the fluid channel 43 , Accordingly, the width 63 the recess 60 in the area of the thread crests (No. 55 in 4 ) at least twice as large as the diameter 44 of the fluid channel 43 ,

4 shows a further rough schematic partial section of the axial piston machine 1 in the region of the recess 60 , The cutting plane contains the central axis of the cylinder bore 50 passing through the fluid channel 43 runs. With respect to this sectional plane, the cross-sectional shape of the recess 60 trapezoidal shaped. The floor area 62 runs parallel to the central axis of the cylinder bore. There, the fluid channel opens 43 completely off. The depth 61 the recess 60 is larger than the thread depth 52 , Accordingly, in the ground area 62 no threads 54 more present, also no remains of a thread 54 , The two depths 61 ; 52 be starting from the thread crests 55 or from the inner diameter of the internal thread 51 measured.

The two opposite side walls 64 the recess 60 are inclined. The flatter the inclination the lower the material stresses occurring during operation.

In 4 is also to recognize that the internal thread 51 directly to the circular cylindrical area 53 borders. Typically, the inner diameter of the circular cylindrical area 53 slightly smaller than the inner diameter of the internal thread 51 so that the thread crests 55 not in alignment with the circular cylindrical area 53 are arranged.

5 shows one of the 4 corresponding partial section of another embodiment of the recess 60 ' , The second embodiment differs from the first embodiment in that 1 to 4 merely in that the cross-sectional shape of the recess 60 ' in the present sectional plane no longer trapezoidal, but is circular. The floor area 62 is therefore not defined anymore. It is rather defined as the area in which no threads 54 more are present, no remains of threads 54 , There, the fluid channel opens 43 completely off.

The circle radius of the cross-sectional shape according to 5 As shown, smaller than the circle radius of the cross-sectional shape 3 his. But it is also conceivable to execute the two circle radii identical. The corresponding recess 60 ' can be made for example by means of a ball mill. Its axis of rotation need not be aligned parallel to the central axis of the cylinder bore. It is preferably chosen so that the ball cutter, in particular its shank, does not collide with the housing.

LIST OF REFERENCE NUMBERS

10

axial piston

11

casing

12

Housing body

13

connecting plate

20

drive shaft

21

drive journal

22

pivot bearing

23

cylinder drum

24

feather

25

pressure ring

26

Rotary axis of the drive shaft

27

working space

30

working piston

31

shoe

32

pivoting cradle

33

retraction plate

34

control plate

35

swivel axis

40

actuating piston

41

Screw

42

cylinder space

43

fluid channel

44

Diameter of the fluid channel

45

piston rod

50

bore

51

inner thread

52

thread depth

53

circular cylindrical area

54

thread

55

threaded tip

56

Center axis of the cylinder bore

60

recess

60 '

Recess (second embodiment)

61

Depth of the recess

62

floor area

63

Width in the area of the thread crests

64

Side wall

70

milling cutter

71

Cutting diameter

72

axis of symmetry

Claims (5)

Axial piston machine (10) having a housing (11) which is provided with a cylinder bore (50), wherein in the cylinder bore an actuating piston (40) is received linearly movable, wherein by means of the actuating piston (40) a displacement volume of the axial piston machine (10) is adjustable , wherein the cylinder bore (50) is provided at an outwardly open end with an internal thread (51) into which a closure screw (41) is screwed, so that between the control piston (40) and the closure screw (41) has a closed cylinder space (42), wherein in the housing (11) a fluid channel (43) is arranged, which is fluidically connected to the cylinder space (42), characterized in that in the region of the internal thread (51) has a recess (60; 60 ') which is deeper than a thread depth (52) of the internal thread (51), so that a bottom portion (62) of the recess (60; 60 ') is free of threads (54), wherein the fluid channel (43) in ge called bottom region (62) opens. Axial piston machine after Claim 1 wherein the recess (60; 60 '), when viewed in a sectional plane which is aligned perpendicular to the central axis (56) of the cylinder bore (50) and which passes through the fluid channel (43), is circular in shape, so that its width ( 63) in the region of the thread crests (55) of the internal thread (51) is at least twice as large as the diameter (44) of the fluid channel (43). Axial piston machine according to one of the preceding claims, wherein the recess (60), when viewed in a sectional plane containing the central axis (56) of the cylinder bore (50) and which extends through the fluid channel (43), is trapezoidal, wherein the fluid channel ( 43) opens completely in the corresponding flat bottom region (62). Axial piston machine after Claim 1 or 2 wherein the recess (60 ') is circular when viewed in a sectional plane containing the central axis (56) of the cylinder bore (50) and passing through the fluid passage (43). Axial piston machine after Claim 3 or 4 wherein the recess (60; 60 ') is rotationally symmetrical with respect to an axis of symmetry which is parallel to the central axis (56) of the cylinder bore (50) and which is disposed inside the cylinder bore (50).

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